Hello all my question is, i am running an ebb and flow system at my house and i have pretty pure well water (50 ppm) well i was having some cal/mag issues so i bought calmag + i read on the internet that i should add the calmag to my resevoir until it reads 200 ppm well my point is my plants need to be at about 500 ppm so im not sure if i need to bring my water to 200 and THEN add 500ppm of nutes or do i need to only put 300 ppm of nutes to bring the total to 500, thank you in advance!